#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
unsigned int DigitSum(unsigned int ret) {
	if (ret < 10)
		return ret;
	else
	return ret % 10 + DigitSum(ret / 10);
}
int main() {

	printf("%d", DigitSum(3333));

	return 0;
}